Donkey Kong Jr. (sometimes referred to as DK Jr. or just Junior) is a Kong character that debuted in Donkey Kong Jr. as the titular hero, who had to save his father, Donkey Kong, from Mario. He is implied to either be the young form of the current Donkey Kong or the father of the current Donkey Kong.

Donkey Kong Jr.'s premier appearance is in the eponymous Donkey Kong Jr. He is the star of the game and the only playable character. It follows the events of the original Donkey Kong, where Donkey Kong Jr.'s father, Donkey Kong has now been locked up by Mario. Donkey Kong Jr. must travel through four stages, climbing vines to ascend them and then watching as Mario hauls his father further on through the game.

There are numerous enemies that Donkey Kong Jr. must avoid. However, if he drops fruit on the enemies, they will be defeated. Once Donkey Kong Jr. has put a key into the cage, Mario will move further on. When Donkey Kong Jr. beats Mario at last in Stage 4, Donkey Kong and Mario both fall; Donkey Kong Jr. catches his father and then walks off-screen with his newly-freed papa.

One year later, Donkey Kong Jr. made another playable appearance in the game Donkey Kong Jr. Math. His father stood at the top of the stage, holding a sign with a random number placed on it instead of being kidnapped by Mario. Donkey Kong Jr. had to climb amongst multiple vines to gather the correct numbers and mathematical signs to create the number on his father's sign.

This game also starred a pink-colored pallete swap of Donkey Kong Jr. that could be playable in a two-player game; however, Donkey Kong Jr. was still brown in color, and could be played as in both one- and two-player modes.

In Donkey Kong on the Game Boy, Donkey Kong Jr. teams up with his father to kidnap Pauline, and Mario must defeat both of them before rescuing her. For most of the game, Donkey Kong Jr. usually stays in areas inaccessible by Mario, activating and deactivating switches in ways that can either help or harm Mario. Sometimes, Donkey Kong Jr. even appears out in the open and throws Poison Mushrooms. He defeats Mario instantly if he touches him. Finally, Mario got to stop him for good in Stage 9-4, where he locked him in a cage in a fashion similar to Stage 4 of the original Donkey Kong Jr.. In the ending, Donkey Kong Jr. somehow managed to free himself and lay in wait as Pauline gave Mario a Super Mushroom to catch Donkey Kong, and acted as soon as his father was calling for help, although they presumably buried the hatchet.

Donkey Kong Jr., voiced by Frank Welker, is featured as the main protagonist of the cartoon short Donkey Kong Junior from the animated series Saturday Supercade. Here, Donkey Kong Jr., after discovering his father is missing from the circus, decides to track him down with the help of a clumsy biker named Bones.

Donkey Kong Jr. makes an appearance in the sixth Nintendo Adventure Book, Doors to Doom; in the book, Mario and Luigi find themselves in Donkey Kong Jr.'s jungle after entering one of the doorways created by Dr. Sporis Von Fungenstein. Upon seeing Mario and Luigi, Donkey Kong Jr. attacks them, forcing the two to flee. Eventually, after a vine-climbing chase, the Mario Bros. escape Donkey Kong Jr.

In 1992, Donkey Kong Jr. appeared as a playable character in Super Mario Kart for the Super Nintendo Entertainment System. He was classified as a heavyweight character alongside Bowser. His preferred item was the Banana, with which he would litter the racecourses. His kart had maximum top speeds; however, if he were to drift away from the main course, its speed would decrease greatly. In every Mario Kart title since Mario Kart 64, he has been replaced by the modern Donkey Kong. Nearly identical look-alikes also appear as a cameo in the background of Waluigi Stadium in Mario Kart: Double Dash!!

Donkey Kong Jr. also made an appearance as an unlockable playable character in 2000, in the Nintendo 64 adaption of Mario Tennis. He was classified as a Power Character, who could be secretly unlocked (alongside Shy Guy). In this game, Donkey Kong Jr. is unlocked by winning the Star Cup in Doubles. Also, his default doubles partner in this game is Donkey Kong.

Donkey Kong Jr. appeared many times in the Game & Watch Gallery installments. Donkey Kong Jr. appears in the first two games with role as a "damsel in distress" in several of the minigames. However, Donkey Kong Jr. is the star of his own minigame which is a small remake of the original Donkey Kong Jr.Game & Watch game. The same minigame from the third game also appears in the fourth installment of the series.

In Super Smash Bros. Brawl, Donkey Kong Jr. did not return as a collectible trophy, though data extracted from the disc shows that he going to appear but was scrapped. Instead, he has a Sticker. The sticker shows Donkey Kong Jr. with a key over his head; the sticker is only referred to as Junior. It raises launch resistance by twenty-one in the Subspace Emissary adventure mode of the game. His other sticker shows him holding a tennis racket from Mario Tennis. Additionally, one of the names that appears when the player presses the "Random Name" button when naming their custom stage is DKJR.

In the second arcade (and second overall) game in the Punch Out!! series, Donkey Kong Jr. could be found in the audience again, along with Mario, Luigi, and Donkey Kong, this time with a different color scheme.

Donkey Kong Jr. came to the rescue when Mario imprisoned his father. DK Jr.'s challenge was to collect the keys to Donkey Kong's cage, all the while dropping fruit on his enemies from high above. He was able to climb faster by using two ivy vines at once. This ape is also quite skilled at kart racing, tennis, and mathematics.

Oddly, several games in which Donkey Kong Jr. cameos contain doppelgängers. Such examples of these games include the Game & Watch Gallery series of remastered compilations (which seem to depict Donkey Kong Jr. as a species rather than an individual character), Donkey Kong Jr. Math which includes a second Donkey Kong Jr. recolored pink, and Mario Kart: Double Dash!! which includes DK Jr.-like audience members at Waluigi Stadium.

Cranky, who is often said to be the original Donkey Kong, is referred to as either the current Donkey Kong's father or grandfather. If the former is true, this would make Donkey Kong Jr. the current Donkey Kong, and if the latter is true then this would make Donkey Kong Jr. father of the current Donkey Kong (which is most likely the case).

During development of Donkey Kong Country, Diddy Kong was originally intended to be a redesign of Donkey Kong Jr., though Nintendo did not like the complete redesigning of the character and ordered that either Donkey Kong Jr. have his original appearance or the redesign be made into a new character.[1]